.\"	$OpenBSD: random.4,v 1.3 1997/06/25 22:28:29 angelos Exp $
.\"
.\" Copyright (c) 1996, 1997 Michael Shalayeff
.\"
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.\"	This product includes software developed by Michael Shalayeff.
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.Dd March 25, 1996
.Dt RND 4
.Os OpenBSD
.Sh NAME
.Nm random ,
.Nm srandom ,
.Nm urandom ,
.Nm prandom ,
.Nm arandom
.Nd random data source devices.
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <dev/rndvar.h>
.Fd #include <dev/rndioctl.h>
.Sh DESCRIPTION
The
.Nm
device produces random data, with different random quality.
{u,s,a}random devices generates random data based on the system activity
(like disk and network devices).
.Pp
.Bl -hang -width /dev/srandomXXX
.It /dev/random
reserved for nuclear noise generators.
.It /dev/srandom
strong random data.
.It /dev/urandom
same as above, but does not guarantees the data to be strong.
.It /dev/prandom
simple pseudo-random generator (as it is in the kernel).
.It /dev/arandom
aRC4 hashed data (as apposed to the {u,s}random, as they are MD5).
.Sh SEE ALSO
.Xr random 9 ,
.Xr random 3 ,
.Xr md5 9 ,
.Xr md5 3 ,
.Xr arc4random 3 .
.Sh FILES
.Bl -tag -width /dev/srandom
.It Pa /dev/random, /dev/srandom, /dev/urandom, /dev/prandom, /dev/arandom
.El
.Sh BUGS
No randomness testing suite provided.
.Sh HISTORY
An
.Nm
device first appeared in Linux operating system.
.Pp
aRC4 routines added by David Mazieres.